Electro-luminescent devices which emit light in the wavelength range between 1.2 micrometers and about 1.7 micrometers are used as light sources in fiber optic communication systems. Typically, light emitting diodes and injection laser diodes composed of group III-V compounds are used for this application. Such devices employ a multiplicity of layers of differing composition and require a large number of different processing steps in their fabrication. It would be desirable to have a device which emits light in this wavelength range but which is simpler to fabricate.
Silicon exhibits a luminescence at about 1.1 micrometers which is weak since the band-to-band optical transitions are indirect. Weak luminescence associated with structural defects in the silicon lattice has also been observed at a number of different wavelengths in silicon which has been irradiated with energetic particles such as ions or electrons. A much stronger luminescence in the wavelength range between about 1.0 micrometers and about 1.2 micrometers has been observed in amorphous silicon formed from the decomposition of silane in a glow discharge. In each of these cases the luminescence is either too weak to be useful as a light source or is outside the wavelength range of interest.